speed time and distance quiz 1

Explanations Speed = Distance/Time = 540/3x180 km/hr. To convert speed into m/s we need to multiply 180 by 5/18. So required speed = 180 × 5/18 = 50 m/s.

Explanations Total distance = 120 + 180 = 300 km. Time taken for the first 120 km = 120/20 → 6 hrs. Time taken for the next 180 km = 180/45 → 4 hrs. Total time taken = 6 + 4 = 10 hrs. Average Speed =Total Distance Travelled/Total Time Taken = 300/10 = 30 km/hr.

Explanations Distance travelled in first 2 hours =10 × 2 = 20 km. Distance travelled in next 1 hour =13 × 1 = 13 km. Total Distance travelled = 20 + 13 = 33 km. Total time taken = 2 + 1 = 3 hrs. Average Speed =Total Distance Travelled/Total Time Taken =33/3 = 11 km/hr.

Explanations (45 + 65) ÷ 2 = 55 kmph. The total distance traveled by the motorist in these two hours = 65 + 45 = 110 km and he has taken two hours. Therefore, his average speed = 55 kmph.

Explanations   Let the distance between the office and Pimpri class be x km. ∴Time taken on my onward journey = x/30 hours and time taken on my return journey = x/45 . ∴The total time taken for my onward and return journey = x/30 + x/45 = 5x/90 hours. The total distance traveled both ways = 2x km ∴ Average speed = 2x/(5x/90) = 36 kmph.

Explanations 40 x 15/60 = 10 km. The important point to note is that time given was in minutes, whereas the speed was in kmph. Therefore, either speed will have to be expressed as km/min or time will have to be expressed in hours to apply the relationship. In this case we converted time into hours to get the answer. Conversely, converting speed into km/min, we get 40 kmph = 40/60 km/min = 2/3 km/min. Therefore, distance traveled = 15 x 2/3 = 10 km.

Explanations Time = Distance ÷ Speed → 60/50 = 1.2 hours = 1 hour and 12 minutes.

Explanations Usual time taken = 50 minutes = 5/6 hours. The distance = 60 km. Usual Speed = Distance ÷ Usual Time → 60/(5/6) = 72 kmph. Speed on this occasion = Distance ÷ Time on this occasion = 60/1 = 60 kmph. The ratio between the usual speed to the speed on this occasion = 72/60 = 6/5 The ratio of the usual time taken to the time taken on this occasion = 50min/60min = 5/6

Explanations Speed in m/sec = 60 x 5/18 = 50/3 m/sec. Time taken to cross the man = 6 seconds. Therefore, distance traveled = 50/3 x 6 = 100 m = length of the train.

Explanations As both the trains are moving in the same direction, the relative speed of the faster train is 60 – 24 = 36 kmph. The relative speed in m/sec = 36 x 5/18 = 10 m/sec. Time taken = 30 sec. Therefore, distance traveled = 10 × 30 = 300 m = Combined length of two trains.